"They have Reavers. And Brumaks almost as tall as the walls. And on that day, we'll be fish in a barrel. We're trapped here."

— Edouain, explaining to Reeve how the prison is doomed if the Locust keep advancing

In Gale of 11 A.E., Edouain gathered with several other inmates and looked over a new issue of the Jacinto Daily. They all grew concerned about a map in the newspaper which showed the Locust lines advancing towards the prison.[3] After witnessing Daniel Merino and Marcus Fenix get into a fight, Edouain started his cleaning duties, mopping the main floor of the cell block. Officer Nikolai Jarvi arrived on the gantry above the floor and asked him if anyone had left since 0600, and Edouain informed him that William Alva had been taken to see the medic a while ago, and that Marcus had been sent to solitary after the fight. Jarvi demanded that Edouain find Millton Reeve, who Jarvi was paying to protect Marcus, and tell him to wait for Jarvi at the checkers table until he returned.[4] The next day, Edouain was looking over his "worry" map, which he put together using maps that came in the Jacinto Daily and used to keep track of how close the Locust were advancing and how quickly they were moving over the years. When Reeve arrived to deliver food, Edouain showed him the map and claimed that the Locust would soon overrun the prison, and that even if they could not dig in due to the solid granite base under them, their war beasts could always knock down or fly over the prison walls. Reeve wondered what they could do to escape before that happened, and Edouain suggested that they tunnel out, even though it would take a long time. After taking a bowl of casserole from the food cart, he asked if Reeve would help gather resources and dig the tunnel, and Reeve agreed to join Edouain's plan.[5]

"Back in the war both you and I remember COG. A hundred useful facts for a saboteur about the enemy and its heartland. Your electricity company built inspection plates every kilometer inside the borough limits."

— Edouain to Marcus, after being asked why he knew so much about Ephyra's utility conduits

Later that fall, Edouain had recruited several other prisoners to help begin digging an escape tunnel. They began their work in the boiler room, where the others dug the tunnel as Edouain worked out calculations on the back of an old piece of cardboard. Leuchars told them that Officer Bradeley Campbell's son had been killed fighting on the frontlines. Reeve and Vance guessed that Campbell would be looking to take revenge on Marcus, who Campbell hated for his actions during the Battle of Ephyra. Edouain asked Reeve if he thought that might motivate Marcus to help them, but Reeve claimed that Marcus did not want to escape and believed he belonged in the Slab. He attempted to convince him anyway, but reported back to Edouain that Marcus was not interested. Edouain was disappointed, but not surprised, and after helping Vance out of the hole, they all headed back to the cell block.[6] By Gale of the next year, Marcus had joined Edouain's crew after Campbell had set dogs on him and Reeve, making him determined to escape and rejoin the fight against the Locust. As Vance and Leuchars worked on digging the hole, Edouain used a sack to haul the dug up soil across the floor and dump it in buckets. Marcus and Reeve arrived to help, and Marcus told Edouain that they were going to have to dig further down to get under the walls, but the granite would stop them. Edouain told him that they were aiming for the utility conduit to get around that obstacle, but Marcus did not think it was a good idea. Edouain asked if he had a better idea, and told him to follow his orders then when Marcus admitted he did not. Vance emerged a moment later and told them he believed he had reached the conduit. Marcus began listing the tools they would need to break into the conduit and asked Edouain where he planned on coming up. He brought out his map and showed the others the location of an inspection hatch seven hundred meters from the prison, explaining that he had been briefed on COG regulation electricity grids during the previous war. Marcus went down into the hole to inspect the conduit, and returned several minutes later with bad news: the pipe was a little under a meter tall, not two and a half like Edouain had been briefed was standard. Edouain claimed they would be fine crawling out of there instead of walking, and asked if there was any more bad news. Marcus then told them that the Locust had gotten into Ephyra through tunnels like that one, and that they might be risking letting the Locust into the prison.[7]

They continued working later that day, and Merino came by to view Edouain's progress, asking where they were going to go once they escaped, pointing out the COG would think they were likely Stranded if they did not figure out they were escaped prisoners and probably be conscripted. Leuchars said he would join the Stranded, but Edouain told them he would head back to Pelles and see if he could find what was left of his people. Merino said he would wave goodbye to him when he left, and left them to continue their work. They were joined a few minutes later by Marcus, and Edouain sent him in for a shift digging the hole. Edouain directed Vance to wash the dirt off himself so the warders did not notice what they were doing. Marcus began sending buckets to them really quickly, and called out to them that the mud was getting softer. A few minutes later, Marcus called out that there was a problem, and they heard a loud noise coming from the hole. Marcus yelled that it was flooding, and they attempted to pull Marcus out of the hole using the rope, but it broke. Edouain and Vance held Reeve's legs as he leaned into the hole to help pull Marcus out. They managed to rescue him, and Edouain asked what happened to the flashlight. Marcus growled at him to go find it, and they watched as muddy water began bubbling up from the hole, spreading across the floor. They heard a rumbling coming from underground and became worried that Locust might be trying to come through the hole. However, the hole simply began to drain and cleared completely. Reeve asked what they were going to do now, and Edouain stated there had to be another way out, but Marcus simply told him to let him know when it was done, and left, with Reeve following him.[8]

"We should have stuck the psychos in the freezer. Terrible waste of protein."

— Edouain to Reeve, as the prisoners ran low on food supplies

After the power went out near the end of the year, several mechanisms were broken. Edouain managed to fix the fuses for the heating systems, but was unable to fix the doors to the cells.[9] In early Rise of the next year, the Slab was cut off from COG territory when the Locust took the Andius Highway. In the first week of Bloom, Edouain found Reeve in the yard and joked that they should have kept the bodies of the insane inmates, who the other prisoners had slaughtered in the power outage, in the freezer so they could have had a source of protein. Reeve joked that the crazed cannibal Rushkin had been the one with all the recipes, but they had killed him as well. Edouain informed him that the old escape tunnel was flooding again, and that it had started the previous month when a lot of explosions had gone off in the city. Reeve told him that Jarvi had said the COG had blown up some sewer lines to halt the Locust advance, a strategy which Edouain felt had not worked well for them.[10] The Locust lines were pushed back in late Rise, allowing the prison to be resupplied.[11]

"Come and admire our ingenuity, Officer Jarvi. Behold the walls of the castle and the boiling oil that awaits the unwary invader."

— Edouain, as he showed Jarvi the defenses the prisoners set up in the boiler room

In Gale of the next year, the water boiler began leaking. Edouain attempted to fix it, but lacked the parts to stop the problem. He met with Marcus, Reeve, and Vance in the boiler room to see if they could figure something out. Marcus noted that Edouain's repairs had managed to slow the leak, but Edouain told him that all the plumbing in the prison was breaking down and that they may need to use wood-fueled fires to keep warm and heat baths soon. Vance noted that the psych wing was flooded, and Edouain wondered if they could go in there and scavenge some pipes to make repairs in their cell block. Marcus managed to retrieve some pipes, but they had to be used as weapons when baby Corpsers emerged from the toilets. Edouain gathered with the rest of the inmates on the main floor of the cell block while Jarvi and the other Warders contacted the army for orders. They gathered all the improvised weapons they could and Edouain listened with the others as Marcus briefed them on other kinds of Locust creatures that could breach the prison.[12] Edouain went with Marcus, Reeve, and Vance back to the boiler room, where they set to work rerouting the boiler tank to send burning water down the hole they had dug, which had drained once again and could allow the Locust creatures access to the prison. Jarvi showed up and Edouain briefed him on their plan, comparing it to Silver Age tactics of defending castles. Edouain and Vance manned the boiler while the others left to investigate the rest of the prison's defenses, but Marcus, Reeve, and Jarvi soon returned. Edouain heard something crawling up the pipes and ordered the water to be poured down the hole, which burned several Wretches. Edouain leaned down into the hole to see if they were all dead, but one extremely burned Wretch had survived and jumped out, hitting him in the face and knocking him back. Marcus killed it, and Edouain and the others stared in horror at the first Wretch they had ever seen. They continued to pour boiling water into the hole whenever they heard something moving, killing several more Wretches.[13] Edouain later evacuated to A Wing with the rest of the prisoners and the warders, except for Marcus and Reeve, and they were eventually rescued by a platoon of Gears.[14]

Edouain referred to Gears as "COG's", like many Indie soldiers.[4] He held a grudge against the COG, not caring that the war was long over. He thought of himself as a political prisoner who did not belong in prison with criminals.[15] While in the Slab, Edouain preferred to keep to himself, staying away from the other inmates in his cell on the south end of D Wing.[2]